celestial equator
Quick Summary
The celestial equator is an imaginary line in astronomy that mirrors Earth's equator. It's the great circle on the celestial sphere, midway between the celestial poles. This line is formed by projecting Earth's equator onto the celestial sphere.12
The celestial equator is significant because it forms the basis for the equatorial coordinate system, which uses right ascension and declination to map celestial objects, analogous to longitude and latitude on Earth. Due to the precession of Earth's axis, the celestial equator's position relative to the stars changes over long periods. This motion causes the celestial poles and the celestial equator to trace circles in the sky.34
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
Equatorcelestial equator is the great circle in which the plane of the terrestrial Equator intersects the celestial sphere; it consequently is equidistant from the celestial poles. When the Sun lies in its plane, day and night are everywhere of equal length, a twice-per-year occurrence (about…
Read Morecelestial equator is the great circle in which the plane of the terrestrial Equator intersects the celestial sphere; it consequently is equidistant from the celestial poles. When the Sun lies in its plane, day and night are everywhere of equal length, a twice-per-year occurrence (about…
Read More
astronomical mapThe celestial sphere…the two poles is the celestial equator; this great circle is the projection into space of Earth’s Equator.
Read More…the two poles is the celestial equator; this great circle is the projection into space of Earth’s Equator.
Read More
